After a very difficult winter - freeze, thaws and heat- the rhododendron is looking awful. Many of the old leaves are brown. This might have happened awhile ago. I just noticed it last week when the weather got warm enough for me to go outside again and garden.
I haven't noticed increasing browning over the last few days, so I don't know if it is progressing or not.
The new growth looks healthy.
Any help is greatly appreciated.
Here are some links that might help:
Azalea and Rhododendron Diseases
http://www.ppath.cas.psu.edu/EXTENSION/PLANT_DISEASE/aza_rhod.html
Azalea and Rhododendron Diseases (this one is more user friendly)
http://hgic.clemson.edu/factsheets/HGIC2050.htm
X
If it was just brown around the leaf edges then I would say it's just cold damage and as long as some of the leaves are still green it'll probably be fine, but with the spots and things that are on there along with the brown edges it does look like some sort of fungus or other disease on top of a little bit of cold damage--hopefully the links above will help you figure out what it is.
I read both sites, thank you!, and I don't see a smiliar description. So perhaps it isn't a disease (or only a disease).
But just in case it is a fungus, have either of you used any of the following on rhodos?
Examples: Bordeaux 4-4-100, copper hydroxide, copper salts of fatty acids or chlorothalonil.
ROX
I still think it could be a fungus of some sort, most likely the leaf spot fungus that they talk about on those sites, that sounds the closest at least. If it was just winter damage, it would be a solid sort of brown color around the leaf edges, not with spots like what you have. I've never had problems on rhodies/azaleas but I did have a crabapple that used to get leaf spot and I tried the copper salts on it, didn't work but I think it's because I didn't have a good sprayer and was only able to get to the very bottom leaves on the tree.
I think to be safe I will treat it with a fungicide.
Today we not only had a hard freeze (20F after 2 weeks of 65-80F), but we also had icing.
I can't imagine what the plants must be going through. It's going to be a really rough summer I think with lost of diseases due to increased susceptibility.
ROX
http://extension.unh.edu/FHGEC/documents/evergren1.pdf
Try this site from NH. I'm in the NE, too, where our weather has been brutal.
